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Question #43672
The Question
Two distant, mutually incoherent point sources and emit linearly polarized light of wavelength . The electric field vector of the emitted light from both sources makes an angle of with the vertical. A telescope is used to observe these sources. The telescope has a rectangular aperture of width (horizontal) and height (vertical). A special mask is placed over the aperture: the left half () is covered by an ideal linear polarizer with its transmission axis vertical, and the right half () is covered by an ideal linear polarizer with its transmission axis horizontal. What is the minimum angular separation between the two sources along the horizontal direction such that they are just resolved according to the Rayleigh criterion?
Options
- A.
- B.
- C.
- D.
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Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Intuition_Breaker
Train your brain to resist "obvious" answers that are designed to deceive your intuition.
Concepts Behind This Question
Photon Polarization and Selection|Phase Difference vs. Path Difference|Resolving Power Limits|Small Angle Approximation
Why This Question Is Tricky
Common Mistakes
Students incorrectly apply the standard scalar Rayleigh criterion () without accounting for the vector nature of light.
The lethal trap lies in failing to recognize that orthogonal polarization states (created by the split polarizer mask) do not interfere.
Consequently, the aperture does not act as a single coherent slit of width , but rather as two independent slits of width whose intensity patterns superimpose.
This modifies the effective geometry of the diffracting wavefront, doubling the angular spread of the central maximum and degrading the resolving power to .
This tests the deep conceptual understanding that interference requires parallel electric field components.
Quick Facts About This Question
Question Information
| Subject | Physics |
| Chapter | Atoms - Class 12 |
| Concept | Photon Polarization and Selection |
| Difficulty | 8 |
| Cognitive Load | 7 |
| Target Solve Time | 160 sec |
| Access | Free |